Reliability Prediction Basics


 Shawn Rice
 2 years ago
 Views:
Transcription
1 Reliability Prediction Basics Reliability predictions are one of the most common forms of reliability analysis. Reliability predictions predict the failure rate of components and overall system reliability. These predictions are used to evaluate design feasibility, compare design alternatives, identify potential failure areas, tradeoff system design factors, and track reliability improvement. The Role of Reliability Prediction Reliability Prediction has many roles in the reliability engineering process. The impact of proposed design changes on reliability is determined by comparing the reliability predictions of the existing and proposed designs. The ability of the design to maintain an acceptable reliability level under environmental extremes can be assessed through reliability predictions. Predictions can be used to evaluate the need for environmental control systems. The effects of complexity on the probability of mission success can be evaluated by performing a reliability prediction analysis. Results from the analysis may determine a need for redundant systems, backup systems, subsystems, assemblies, or component parts. MILHDBK217 (Electronics Reliability Prediction), Bellcore/Telcordia (Electronics Reliability Prediction) and NSWC (Mechanical Reliability Prediction) provide failure rate and MTBF (Mean Time Between Failures) data for electronic and mechanical parts and equipment. A reliability prediction can also assist in evaluating the significance of reported failures. Ultimately, the results obtained by performing a reliability prediction analysis can be useful when conducting further analyses such as a FMECA (Failure Modes, Effects and Criticality Analysis), RBD (Reliability Block Diagram) or a Fault Tree analysis. The reliability predictions are used to evaluate the probabilities of failure events described in these alternate failure analysis models. Reliability and Unreliability First, let us review some concepts of reliability. At a given point in time, a component or system is either functioning or it has failed, and that the component or system operating state changes as time evolves. A working component or system will eventually fail. The failed state will continue forever, if the component or system is nonrepairable. A repairable component or system will remain in the failed state for a period of time while it is being repaired and then transcends back to the functioning state when the repair is completed. This transition is assumed to be instantaneous. The change from a functioning to a failed state is failure while the change from a failure to a functioning state is referred to as repair. It is also assumed that repairs bring the component or system back to an as good as new condition. This cycle continues with the repairtofailure and the failuretorepair process; and then, repeats over and over for a repairable system. The reliability prediction standards such as MIL217, Bellcore/Telcordia and NSWC Mechanical assume the component or system to be nonrepairable, in a new condition at Copyright 2007, ITEM Software, Inc. Page 1 of 9
2 time zero and have a constant failure rate, if evaluated over a very long time period and using an infinite or very large sample size of components or systems. Reliability (for nonrepairable items) can be defined as the probability that an item will perform a defined function without failure under stated conditions for a stated period of time. One must grasp the concept of probabilities in order to understand the concept of reliability. The numerical values of both reliability and unreliability are expressed as a probability from 0 to 1 and have no units. Reliability stated in another way: The Reliability, R(, of a component or system is defined as the probability that the component or system remains operating from time zero to time t 1, given that it was operating at time zero. Or stated another way for repairable items: The Reliability, R(, is defined as the probability that the component or system experiences no failures during the time interval zero to t 1 given that the component or system was repaired to a like new condition or was functioning at t 0. And: The Unreliability, F(, of a component or system is defined as the probability that the component or system experiences the first failure or has failed one or more times during the time interval zero to time t, given that it was operating or repaired to a like new condition at time zero. Or stated another way: The Unreliability, F(, of a component or system at a given time is simply the number of components failed to time t divided by the total number of samples tested. The following relationship holds true since a component or system must either experience its first failure in the time interval zero to t or remain operating over this period. R( + F( = 1 or Unreliability F( = 1 R( Availability and Unavailability In reliability engineering and reliability studies, it is the general convention to deal with unreliability and unavailability values rather than reliability and availability. The numerical value of both availability and unavailability are also expressed as a probability from 0 to 1 with no units. The Availability, A(, of a component or system is defined as the probability that the component or system is operating at time t, given that it was operating at time zero. Copyright 2007, ITEM Software, Inc. Page 2 of 9
3 The Unavailability, Q(, of a component or system is defined as the probability that the component or system is not operating at time t, given that is was operating at time zero. Or stated another way: Unavailability, Q( is the probability that the component or system is in the failed state at time t and is equal to the number of the failed components at time t divided by the total sample. Therefore, the following relationship holds true since a component or system must be either operating or not operating at any time: A( + Q( = 1 Both parameters are used in reliability assessments, safety and cost related studies. The following relationship holds: For a nonrepairable component or system: Unavailability Q( Unreliability F( Unavailability Q( = Unreliability F( NOTE: This general equality only holds for system unavailability and unreliability if all the components within the system are nonrepairable up to time t. Reliability Prediction Definitions Failure Rates Reliability predictions are based on failure rates. Conditional Failure Rate or Failure Intensity, λ(, can be defined as the anticipated number of times an item will fail in a specified time period, given that it was as good as new at time zero and is functioning at time t. It is a calculated value that provides a measure of reliability for a product. This value is normally expressed as failures per million hours (fpmh or 10 6 hours), but can also be expressed, as is the case with Bellcore/Telcordia, as failures per billion hours (fits or failures in time or 10 9 hours). For example, a component with a failure rate of 2 failures per million hours would be expected to fail 2 times in a millionhour time period. Failure rate calculations are based on complex models which include factors using specific component data such as temperature, environment, and stress. In the prediction model, assembled components are structured serially. Thus, calculated failure rates for assemblies are a sum of the individual failure rates for components within the assembly. There are three common basic categories of failure rates: Copyright 2007, ITEM Software, Inc. Page 3 of 9
4 Mean Time Between Failures (MTBF) Mean Time To Failure (MTTF) Mean Time To Repair (MTTR) Mean Time Between Failures (MTBF) Mean time between failures (MTBF) is a basic measure of reliability for repairable items. MTBF can be described as the time passed before a component, assembly, or system fails, under the condition of a constant failure rate. Another way of stating MTBF is the expected value of time between two consecutive failures, for repairable systems. It is a commonly used variable in reliability and maintainability analyses. MTBF can be calculated as the inverse of the failure rate, λ, for constant failure rate systems. For example, for a component with a failure rate of 2 failures per million hours, the MTBF would be the inverse of that failure rate, λ, or: 1 1 MTBF = OR = 500,000hours / λ 6 2Failures /10 hours failure NOTE: Although MTBF was designed for use with repairable items, it is commonly used for both repairable and nonrepairable items. For nonrepairable items, MTBF is the time until the first (an only) failure after t 0. Mean Time To Failure (MTTF) Mean time to failure (MTTF) is a basic measure of reliability for nonrepairable systems. It is the mean time expected until the first failure of a piece of equipment. MTTF is a statistical value and is intended to be the mean over a long period of time and with a large number of units. For constant failure rate systems, MTTF is the inverse of the failure rate, λ. If failure rate, λ, is in failures/million hours, MTTF = 1,000,000 / Failure Rate, λ, for components with exponential distributions. Or 1 MTTF = 6 λ failures /10 hours For repairable systems, MTTF is the expected span of time from repair to the first or next failure. Mean Time to Repair (MTTR) Mean time to repair (MTTR) is defined as the total amount of time spent performing all corrective or preventative maintenance repairs divided by the total number of those repairs. It is the expected span of time from a failure (or shut down) to the repair or maintenance completion. This term is typically only used with repairable systems. Failure Frequencies There are four failure frequencies, which are commonly used in reliability analyses. Copyright 2007, ITEM Software, Inc. Page 4 of 9
5 Failure Density f (  The failure density of a component or system, f (, is defined as the probability per unit time that the component or system experiences its first failure at time t, given that the component or system was operating at time zero. Failure Rate r (  The failure rate of a component or system, r (, is defined as the probability per unit time that the component or system experiences a failure at time t, given that the component or system was operating at time zero and has survived to time t. Conditional Failure Intensity (or Conditional Failure Rate) λ (  The conditional failure intensity of a component or system, λ (, is defined as the probability per unit time that the component or system experiences a failure at time t, given that the component or system was operating, or was repaired to be as good as new, at time zero and is operating at time t. Unconditional Failure Intensity or Failure Frequency ω (  The unconditional failure intensity of a component or system, ω (, is defined as the probability per unit time that the component or system experiences a failure at time t, given that the component or system was operating at time zero. Relationships Between Failure Parameters The following relations exist between failure parameters. R ( + F( = 1 df( f ( = dt F( = t f ( u). du 0 f ( r( = 1 F( R 0 ( = e F t = e 0 ( ) 1 t r( u). du t f t = r t e 0 ( ) ( ) t r( u). du r( u). du Copyright 2007, ITEM Software, Inc. Page 5 of 9
6 The definitions for failure rate r ( and conditional failure intensity λ ( differ in that that the failure rate definition addresses the first failure of the component or system rather than any failure of the component or system. In the special cases of the failure rate being constant with respect to time or if the component is nonrepairable these two quantities are equal. In summary : λ ( t ) =r( for nonrepairable components λ ( t ) =r( for constant failure rates λ ( r( for the general case The difference between the conditional failure intensity (CFI) λ ( and unconditional failure intensity ω ( is that the CFI has an additional condition that the component or system has survived to time t. The relationship between these two quantities may be expressed mathematically as ω ( =λ( [1 Q( ] For most reliability and availability studies the unavailability Q ( of components and systems is very much less than 1. In such cases ω( λ( Constant Failure Rates If the failure rate is constant then the following expressions apply : R( = e λt F( = 1 e f ( e λt t =λ λ As can be seen from the equation above a constant failure rate results in an exponential failure density distribution. Repairable and Nonrepairable Items It is important to distinguish between repairable and nonrepairable items when predicting or measuring reliability. Nonrepairable items Nonrepairable items are components or systems such as a light bulb, transistor, rocket motor, etc. Their reliability is the survival probability over the items expected life or over a specific period of time during its life, when only one failure can occur. During the component or systems life, the instantaneous probability of the first and only failure is called the hazard rate or failure rate, r (. Life values such as MTTF described above are used to define nonrepairable items. Copyright 2007, ITEM Software, Inc. Page 6 of 9
7 Repairable Items For repairable items, reliability is the probability that failure will not occur in the time period of interest; or when more than one failure can occur, reliability can be expressed as the failure rate, λ, or the rate of occurrence of failures (ROCOF). In the case of repairable items, reliability can be characterized by MTBF described above, but only under the condition of constant failure rate. There is also the concern for availability, A(, of repairable items since repair takes time. Availability, A(, is affected by the rate of occurrence of failures (failure rate, λ) or MTBF plus maintenance time; where maintenance can be corrective (repair) or preventative (to reduce the likelihood of failure). Availability, A(, is the probability that an item is in an operable state at any time Availability ( ) At = MTBF MTBF + MTTR Some systems are considered both repairable and nonrepairable, such as a missile. It is repairable while under test on the ground; but becomes a nonrepairable system when fired. NOTE: Failure rate, λ, is applied loosely to nonrepairable items. What is really meant in a repairable system, which contains a part, is that the part will contribute to the overall system failure rate by the stated part failure rate. The part being nonrepairable cannot have a failure rate. Failure Patterns (Nonrepairable Items) There are three patterns of failures for nonrepairable items, which can change with time. The failure rate (hazard rate) may be decreasing, increasing or constant. 1. Decreasing Failure Rate (Nonrepairable Items) A decreasing failure rate (DFR) can be caused by an item, which becomes less likely to fail as the survival time increases. This is demonstrated by electronic equipment during their early life or the burnin period. This is demonstrated by the first half of the traditional bath tub curve for electronic components or equipment where failure rate is decreasing during the early life period. 2. Constant Failure Rate (Nonrepairable Items) A constant failure rate (CFR) can be caused by the application of loads at a constant average rate in excess of the design specifications or strength. These are typically externally induced failures. 3. Increasing Failure Rate (Nonrepairable Items) An increasing failure rate (IFR) can be caused by material fatigue or by strength deterioration due to cyclic loading. Its failure mode does not accrue for a finite time, then exhibits an increasing probability of occurrence. Copyright 2007, ITEM Software, Inc. Page 7 of 9
8 This failure pattern is also demonstrated by electronic equipment that has aged beyond its useful life (right hand side of the bath tub curve) and the failure rate is rapidly increasing with time. Typical Bath Tub Curve Early Life or High Failure Rate Stage (Failure of Weak or Defective Components) (Burnin Period) Wearout or Increasing Failure Rate Stage (End of Useful Life) Failure Rate r( Steadystate or Constant Failure Rate Stage PrimeofLife (Failures Occur Randomly) Failures Age (Useful Life) Externally Induced Figure 1 Typical Bath Tub Curve Failure Patterns (Repairable Items) There are three patterns of failures for repairable items, which can change with time. The failure rate (hazard rate) may be decreasing, increasing or constant. 1. Decreasing Failure Rate (Repairable Items) An item whose reliability is improved by progressive repair and / or burnin can cause a decreasing failure rate (DFR) pattern. 2. Constant Failure Rate (Repairable Items) A constant failure rate (CFR) is indicative of externally induced failures as in the constant failure rate of nonrepairable items. This is typical of complex systems subject to repair and overhaul. 3. Increasing Failure Rate (Repairable Items) Copyright 2007, ITEM Software, Inc. Page 8 of 9
9 This increasing failure rate (IFR) pattern is demonstrated by repairable equipment when wear out modes begin to predominate or electronic equipment that has aged beyond its useful life (right hand side of the bath tub curve) and the failure rate is increasing with time. Redundancy Redundancy is briefly defined as the existence of two or more means, not necessarily identical, for accomplishing a given single function. There are different types of redundancy. Active Redundancy Has all items operating simultaneously in parallel. All items are working and in use at the same time, even though only one item is required for the function. There is no change in the failure rate of the surviving item after the failure of a companion item. Pure Parallel No Change in the failure rate of surviving items after failure of a companion item. Shared Parallel Failure rate of remaining items change after failure of a companion item. Standby Redundancy Has alternate items activated upon failure of the first item. Only one item is operating at a time to accomplish the function. One item s failure rate affects the failure characteristics of others as they are now more susceptible to failure beause they are now under load. Hot Standby Same as Active Standby or Active Redundancy. Cold Standby (Passive) Normally not operating. Do not fail when they are on cold standby. Failure of an item forces standby item to start operating. Warm Standby Normally active or operational, but not under load. Failure rate will be less due to lower stress. Routofn Systems Redundant system consisting of n items in which r of the n items must function for the system to function (voting decision). Copyright 2007, ITEM Software, Inc. Page 9 of 9
The purpose of this procedure is to document the process for generating Reliability Block Diagram (RBD) for Sydney Water s facility assets.
Procedure Reliability Block Diagram (RBD). Overview.. Objective The purpose of this procedure is to document the process for generating Reliability Block Diagram (RBD) for Sydney Water s facility assets..2.
More informationMean Time Between Failure (MTBF)
Mean Time Between Failure (MTBF) by Vance Persons, Joseph Dykshorn Introduction MTBF stands for Mean Time Between Failures. It is a term that represents reliability of a given product. We will discuss
More informationSystem risks, reliability and costs
System risks, reliability and costs Systems always have risks attached to them. How do we deal with risks? How reliable are systems? And what do systems cost anyway? That s what we ll look at in this chapter.
More information"Reliability and MTBF Overview"
"Reliability and MTBF Overview" Prepared by Scott Speaks Vicor Reliability Engineering Introduction Reliability is defined as the probability that a device will perform its required function under stated
More informationReliability Workbench
Reliability Workbench RELIABILITY WORKBENCH Reliability Workbench incorporating FaultTree+ is the world leading software suite for reliability and safety analysis of systems. It is widely used in industries
More informationDesign for X. Objectives of the session
Design for X Dr Jane Marshall Product Excellence using 6 Sigma Module PEUSS 2012/2013 Design for X Page 1 Objectives of the session Introduce Design for X Discuss Specific Design for X methods PEUSS 2012/2013
More informationReliability Block Diagram RBD
Information Technology Solutions Reliability Block Diagram RBD Assess the level of failure tolerance achieved RELIABIL ITY OPTIMIZATION System reliability analysis for sophisticated and large scale systems.
More informationMAINTAINED SYSTEMS. Harry G. Kwatny. Department of Mechanical Engineering & Mechanics Drexel University ENGINEERING RELIABILITY INTRODUCTION
MAINTAINED SYSTEMS Harry G. Kwatny Department of Mechanical Engineering & Mechanics Drexel University OUTLINE MAINTE MAINTE MAINTAINED UNITS Maintenance can be employed in two different manners: Preventive
More informationManaging Building Services Maintenance Risk with Prediction Theories
Managing Building Services Maintenance Risk with Prediction Theories K. C. Lam Dept. of Building Services Engineering The Hong Kong Polytechnic University Hong Kong Abstract When building services maintenance
More informationChapters 3 and 4 Fault Tree Analysis
Chapters 3 and 4 Fault Tree Analysis Marvin Rausand marvin.rausand@ntnu.no RAMS Group Department of Production and Quality Engineering NTNU (Version 0.1) Marvin Rausand (RAMS Group) System Reliability
More informationProduct Excellence using 6 Sigma (PEUSS)
Section 7 WARWICK MANUFACTURING GROUP Product Excellence using 6 Sigma (PEUSS) Introduction to Reliability AN INTRODUCTION TO RELIABILITY ENGINEERING Contents 1 Introduction 1 2 Measuring reliability 4
More informationReliability of Technical Systems
Reliability of Technical Systems Main Topics 1. Short Introduction, Reliability Parameters: Failure Rate, Failure Probability, etc. 2. Some Important Reliability Distributions 3. Component Reliability
More informationMean Time Between Failure: Explanation and Standards
Mean Time Between Failure: Explanation and Standards By Wendy Torell Victor Avelar White Paper #78 Executive Summary Mean Time Between Failure is a reliability term used loosely throughout many industries
More informationCalculating Reliability using FIT & MTTF: Arrhenius HTOL Model
by Paul Ellerman, Director of Reliability pellerman@microsemi.com Calculating Reliability using FIT & MTTF: Arrhenius HTOL Model Scope Establish a method for calculating the standard reliability values
More informationUsing Fault Trees to Analyze SafetyInstrumented Systems
Using Fault Trees to Analyze SafetyInstrumented Systems Joseph R. Belland Isograph, Inc., Irvine, USA Abstract: Safetyinstrumented systems are protection functions frequently seen in automotive, chemical
More information4.State dependent models
4.State dependent models 4. Markov processes Markov processes can model a system which is considered to be in any one of a discrete set of states fs ; S ; :::; S k g at time t (continuous time). The fundamental
More informationMean Time Between Failure: Explanation and Standards
Mean Time Between Failure: Explanation and Standards White Paper 78 Revision 1 by Wendy Torell and Victor Avelar > Executive summary Mean time between failure is a reliability term used loosely throughout
More informationModule 13. Software Reliability and Quality Management. Version 2 CSE IIT, Kharagpur
Module 13 Software Reliability and Quality Management Lesson 32 Software Reliability Issues Specific Instructional Objectives At the end of this lesson the student would be able to: Differentiate between
More informationIssue 1.0 Jan 2002. A Short Guide to Quality and Reliability Issues In Semiconductors For High Rel. Applications
Issue 1.0 Jan 2002 A Short Guide to Quality and Reliability Issues In Semiconductors For High Rel. Applications It is impossible to test Quality or Reliability into a product. It is, however, quite practical
More informationMTBF, MTTR, MTTF & FIT Explanation of Terms
MTBF, MTTR, MTTF & FIT Explanation of Terms Purpose The intent of this White Paper is to provide an understanding of MTBF and other product reliability methods. Understanding the methods for the lifecycle
More informationItem ToolKit Technical Support Notes
Item ToolKit Notes Managing Product Life Cycle in Item ToolKit 2190 Towne Centre Place Suite 314 Anaheim, CA 92806 Phone: +1.714.935.2900 Fax: +1.714.935.2911 http:// Page 1 of 9 Copyright 2006, All Rights
More informationFault Management for System Safety: Introduction to Fault Tree Analysis
Fault Management for System Safety: Introduction to Fault Tree Analysis Guest Lecture SYST 460/560: Michael Scher 7 December 2009 Overview What is Fault Tree Analysis? Relevant Definitions Role of FTA
More informationCERTIFIED RELIABILITY ENGINEER (CRE) BODY OF KNOWLEDGE
CERTIFIED RELIABILITY ENGINEER (CRE) BODY OF KNOWLEDGE The topics in this Body of Knowledge include additional detail in the form of subtext explanations and the cognitive level at which the questions
More informationCHAPTER 1. Introduction
CHAPTER 1 Introduction This introductory chapter provides an overview of quality and reliability engineering techniques, the relationship between reliability and cost, and reliability, design, and assessment.
More informationAlessandro Birolini. ineerin. Theory and Practice. Fifth edition. With 140 Figures, 60 Tables, 120 Examples, and 50 Problems.
Alessandro Birolini Re ia i it En ineerin Theory and Practice Fifth edition With 140 Figures, 60 Tables, 120 Examples, and 50 Problems ~ Springer Contents 1 Basic Concepts, Quality and Reliability Assurance
More informationAdvancements in LED Technology
Advancements in LED Technology Advancements in LED (Light Emitting Diode) technology have made this source an attractive alternative to traditional light sources in a variety of applications. One such
More informationIntroduction to Basic Reliability Statistics. James Wheeler, CMRP
James Wheeler, CMRP Objectives Introduction to Basic Reliability Statistics Arithmetic Mean Standard Deviation Correlation Coefficient Estimating MTBF Type I Censoring Type II Censoring Eponential Distribution
More informationSoftware Reliability Introduction. Barbara Russo
Software Reliability Introduction Barbara Russo Lessons learned } Reliability concerns the study of failures } There are different notions of effect of an error } Often the difference regards where and
More informationDEDICATED TO EMBEDDED SOLUTIONS
DEDICATED TO EMBEDDED SOLUTIONS RELIABILITY IN SUBSEA ELECTRONICS TECHNIQUES TO OBTAIN HIGH RELIABILITY STIGHELGE LARSEN KARSTEN KLEPPE DATA RESPONS 20121016 AGENDA Introduction Analysis and Design
More informationEmbedded Systems Lecture 9: Reliability & Fault Tolerance. Björn Franke University of Edinburgh
Embedded Systems Lecture 9: Reliability & Fault Tolerance Björn Franke University of Edinburgh Overview Definitions System Reliability Fault Tolerance Sources and Detection of Errors Stage Error Sources
More informationCHAPTER 4 MONTECARLO SIMULATION CONTENTS
Applied R&M Manual for Defence Systems Part D  Supporting Theory CHAPTER 4 MONTECARLO SIMULATION CONTENTS Page 1 SIMULATION AND ANALYTIC MODELS 2 2 COMPARISON OF METHODS 2 3 STATISTICAL ACCURACY OF RESULTS
More informationChapter 8: Reliability and Availability
1 Chapter 8: Reliability is critical to many modern electronic systems. Applications such as routers and wireless base stations generate revenue for the ISP or carrier for only as long as they are available.
More informationC 1 C 2 C i C n C 1 C 2. C i. C n
Exercises 1. A microcomputer system consists of a microprocessor CPU chip and a random access memory chip. The CPU is selected from a lot of 100 of which 10 are defective and the memory chip is selected
More informationCopyright Tyco Electronics Corporation Page 1 of 7
ABSTRACT Reliability is a term which is commonly used. But the actual meaning of reliability and the problems associated with determining it are often not understood. This paper briefly examines reliability
More informationSafety and Reliability of Embedded Systems. (Sicherheit und Zuverlässigkeit eingebetteter Systeme) Safety and Reliability Analysis Models: Overview
1 (Sicherheit und Zuverlässigkeit eingebetteter Systeme) Safety and Reliability Analysis Models: Overview Prof. Dr. Liggesmeyer, 1 Content Classification Hazard and Operability Study (HAZOP) Preliminary
More informationTechnical Note SolarEdge Reliability Methodology
Technical Note SolarEdge Reliability Methodology Summary SolarEdge Technologies develops and sells power electronics for the Photovoltaic market. The heart of the SolarEdge power harvesting system is a
More informationReliability Tools and Analysis Methods for Nuclear Power Plants. Sharon Honecker, PhD Research Scientist ReliaSoft Corporation Tucson, Arizona
Reliability Tools and Analysis Methods for Nuclear Power Plants Sharon Honecker, PhD Research Scientist ReliaSoft Corporation Tucson, Arizona Overview What is reliability? What methods can help me ensure
More informationRANDOM VIBRATION AN OVERVIEW by Barry Controls, Hopkinton, MA
RANDOM VIBRATION AN OVERVIEW by Barry Controls, Hopkinton, MA ABSTRACT Random vibration is becoming increasingly recognized as the most realistic method of simulating the dynamic environment of military
More informationReliability of electronics: HALTtesting. 1 I. Vervenne. Outline. Reliability. Failure rate. Failure rate and reliability. Failure rate calculation
Outline Reliability of electronics: HALTtesting Isabelle Vervenne TUSofia, 9 th September 20 Reliability analysis Some definitions Failure rate of electronic components HALT (highly accelerated life tes
More informationDesigning FaultTolerant Power Infrastructure
Designing FaultTolerant Power Infrastructure System Analysis and New Standards Enable Maximization of Operating Dependability for Data Centers & Other Mission Critical Facilities J.F. Christin (Author)
More informationMilitary Reliability Modeling William P. Fox, Steven B. Horton
Military Reliability Modeling William P. Fox, Steven B. Horton Introduction You are an infantry rifle platoon leader. Your platoon is occupying a battle position and has been ordered to establish an observation
More informationDesigned for uptime. Defining data center availability via a tier classification system
Defining data center availability via a tier classification system MIETEK GLIKOWSKI All systems can fail this is a simple fact that every industry must deal with. The paramount concern for the data center
More informationReliability of Systems and Components
Reliability of Systems and Components GNS Systems GmbH Am Gaußberg 2 38114 Braunschweig / Germany Fri 13 Apr 2012, Revision 0.1.1 Please send comments about this document to: norman.krebs@gnssystems.de
More informationWeibull Analysis of Truck Tyre Failures
Weibull Analysis of Truck Tyre Failures Weibull Analysis has become popular as a means of identifying equipment parts failure patterns. The shape of the failure curve allows us to identify whether the
More informationA System Engineering Reliability Study of the A10 Attack Aircraft using data
A System Engineering Reliability Study of the A10 Attack Aircraft using 2004 2008 data The NDIA 18 th Annual System Engineering Conference October 29, 2015 Joseph Brady Dissertation Topic Department of
More informationCertified Reliability Engineer
Certified Reliability Engineer Quality excellence to enhance your career and boost your organization s bottom line asq.org/certification Certification from ASQ is considered a mark of quality excellence
More informationFault Tree Analysis. Table of Contents
M. Pandey, University of Waterloo CIVE 240 Engineering and Sustainable Development Fault Tree Analysis Table of Contents Introduction... 3 Fault Tree Analysis... 3 Basic Events... 4 Advantages... 4 Limitations...
More informationCalculating Total System Availability
Calculating Total System Availability Hoda Rohani, Azad Kamali Roosta Information Services Organization KLMAir France Amsterdam Supervised by Betty Gommans, Leon Gommans Abstract In a mission critical
More informationReliability aspects on Power Supplies
Reliability aspects on Power Supplies Design Note 002 Ericsson Power Modules General Abstract As power supplies are the very heart of every electronic equipment, special attention must be paid to their
More informationValue Paper Author: Edgar C. Ramirez. Diverse redundancy used in SIS technology to achieve higher safety integrity
Value Paper Author: Edgar C. Ramirez Diverse redundancy used in SIS technology to achieve higher safety integrity Diverse redundancy used in SIS technology to achieve higher safety integrity Abstract SIS
More informationHALT and Reliability Workshop
HALT and Reliability Workshop Elite Electronic Engineering Steve Laya 6304959770 x 119, sglaya@elitetest.com HALT and Reliability Workshop Topics Covered Reliability and Planning Overview of Reliability
More informationReliability Data Analysis
IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making Reliability Data Analysis Lecturer Lesson Lesson IV IV 3_5 3_5 Workshop Information IAEA Workshop City, XX XX  City XX, Country
More informationIndependent analysis methods for Data Centers
Bilfinger HSG Facility Management GmbH Independent analysis methods for Data Centers Max Altmeyer / Marvin Köhler August 19 th, 2015 Agenda 1. Weak point analysis 2. Energy efficiency analysis 3. Combined
More informationThe role of Maintenance Planning in business and its foundation basics
The role of Planning in business and its foundation basics Joe and Ted will take you through the course presentation. Hi Hello! This is Joe. This is Ted. Day 1 of the course Planning and Scheduling exists
More informationcahiers techniques 144
cahiers techniques 144 introduction to dependability design P. Bonnefoi Pascal Bonnefoi earned his engineering degree ESE in 1985. After working for a year in Operational Research for the French Navy he
More informationInternational Journal of Advances in Science and Technology (IJAST)
Determination of Economic Production Quantity with Regard to Machine Failure Mohammadali Pirayesh 1, Mahsa Yavari 2 1,2 Department of Industrial Engineering, Faculty of Engineering, Ferdowsi University
More informationSolving Data Loss in Massive Storage Systems Jason Resch Cleversafe
Solving Data Loss in Massive Storage Systems Jason Resch Cleversafe 2010 Storage Developer Conference. Insert Your Company Name. All Rights Reserved. 1 In the beginning There was replication Long before
More informationChapter 9 Reliability Centered Maintenance
Chapter 9 Reliability Centered Maintenance Marvin Rausand marvin.rausand@ntnu.no RAMS Group Department of Production and Quality Engineering NTNU (Version 0.1) Marvin Rausand (RAMS Group) System Reliability
More information5.0 HARDWARE/SOFTWARE SYSTEM RELIABILITY MODELING
5.0 HARDWARE/SOFTWARE SYSTEM RELIABILITY MODELING Reliability modeling of combined hardware and software systems is in many ways analogous to reliability modeling of purely hardware systems. Reliability
More informationExecutive Summary WHAT IS DRIVING THE PUSH FOR HIGH AVAILABILITY?
MINIMIZE CUSTOMER SERVICE DISRUPTION IN YOUR CONTACT CENTER GENESYS SIP 99.999% AVAILABILITY PROVIDES QUALITY SERVICE DELIVERY AND A SUPERIOR RETURN ON INVESTMENT TABLE OF CONTENTS Executive Summary...1
More informationSTAGEGATING ACCELERATED RELIABILITY GROWTH IN AN INDUSTRIAL ENVIRONMENT. Dana Crowe and Alec Feinberg ESS? HALT? HASS? HAST?
GATING ACCELERATED RELIABILITY GROWTH IN AN INDUSTRIAL ENVIRONMENT Dana Crowe and Alec Feinberg ABSTRACT In this paper, an Accelerated Reliability Growth (ARG) StageGate (SG) process is described that
More informationPART 2 Interpreting Failure Rates...39 Chapter 4: Realistic Failure Rates and Prediction Confidence...41
Contents Preface...xix Acknowledgements...xxi PART 1 Understanding Reliability Parameters and Costs...1 Chapter 1: The History of Reliability and Safety Technology...3 1.1 Failure Data... 3 1.2 Hazardous
More informationReliability of Technical Systems
Main Topics 1. Short Introduction, Reliability Parameters: Failure Rate, Failure Probability, etc. 2. Some Important Reliability Distributions 3. Component Reliability 4. Introduction, Key Terms, Framing
More informationMonte Carlo Simulation using Excel for Predicting Reliability of a Geothermal Plant
Monte Carlo Simulation using Excel for Predicting Reliability of a Geothermal Plant Daniela E. Popescu, Corneliu Popescu, Gianina Gabor University of Oradea, Str. Armatei Romane nr.5, Oradea, România depopescu@uoradea.ro,
More informationPublic Goods : (b) Efficient Provision of Public Goods. Efficiency and Private Goods
Public Goods : (b) Efficient Provision of Public Goods Efficiency and Private Goods Suppose that there are only two goods consumed in an economy, and that they are both pure private goods. Suppose as well
More informationThe Secondary Impact of System Optimisation on Building Equipment; Maintenance and Life Expectancy
ENVIRONMENTAL GROUP The Secondary Impact of System Optimisation on Building Equipment; Maintenance and Life Expectancy Dr. Houman Tamaddon JUNE 2015 INTRODUCTION The increased pace of global energy consumption
More informationGUIDANCE FOR ASSESSING THE LIKELIHOOD THAT A SYSTEM WILL DEMONSTRATE ITS RELIABILITY REQUIREMENT DURING INITIAL OPERATIONAL TEST.
GUIDANCE FOR ASSESSING THE LIKELIHOOD THAT A SYSTEM WILL DEMONSTRATE ITS RELIABILITY REQUIREMENT DURING INITIAL OPERATIONAL TEST. 1. INTRODUCTION Purpose The purpose of this white paper is to provide guidance
More informationFailure Modes, Effects and Diagnostic Analysis
Failure Modes, Effects and Diagnostic Analysis Project: PlantSTOP 9475 Company: R. STAHL Schaltgeräte GmbH Waldenburg Germany Contract No.: STAHL 13/04027 Report No.: STAHL 13/04027 R024 Version V1,
More informationElectric Currents. Electric Potential Energy 11/23/16. Topic 5.1 Electric potential difference, current and resistance
Electric Currents Topic 5.1 Electric potential difference, current and resistance Electric Potential Energy l If you want to move a charge closer to a charged sphere you have to push against the repulsive
More informationThermal Diffusivity, Specific Heat, and Thermal Conductivity of Aluminum Oxide and Pyroceram 9606
Report on the Thermal Diffusivity, Specific Heat, and Thermal Conductivity of Aluminum Oxide and Pyroceram 9606 This report presents the results of phenol diffusivity, specific heat and calculated thermal
More informationIntroduction to Software Reliability Estimation
Introduction to Software Reliability Estimation 1 Motivations Software is an essential component of many safetycritical systems These systems depend on the reliable operation of software components How
More informationComparing the Reliability of Ethernet Network Topologies in Substation Control and Monitoring Networks
Comparing the Reliability of Ethernet Network Topologies in Substation Control and Monitoring Networks Gary W. Scheer and David J. Dolezilek Schweitzer Engineering Laboratories, Inc. Presented at UTC Telecom
More informationBasics of Traditional Reliability
Basics of Traditional Reliability Where we are going Basic Definitions Life and ties of a Fault Reliability Models NModular redundant systes Definitions RELIABILITY: SURVIVAL PROBABILITY When repair is
More informationRajkumar B. Patil 1, L. Y. Waghmode 2, P. B. Chikali 3, T. S. Mulla 4.
IOSR Journal of Mechanical & Civil Engineering (IOSRJMCE) ISSN: 22781684, PP: 1418 www.iosrjournals.org An Overview of Fault Tree Analysis (FTA) Method for Reliability Analysis & Life Cycle Cost (LCC)
More informationCalculation of Semiconductor Failure Rates
Calculation of Semiconductor Failure Rates William J. Vigrass One of the fundamentals of understanding a product s reliability requires an understanding of the calculation of the failure rate. The traditional
More informationFMEA and FTA Vít Hampl
FMEA and FTA Vít Hampl FMEA  Failure mode and effects analysis FMEA is a bottomup technique used to identify, prioritize, and eliminate potential failures from the system, design or process before they
More informationSIL Safety Manual. OXYMAT 6 Gas Analyzer for the Determination of Oxygen. Supplement to instruction manual ULTRAMAT 6 and OXYMAT 6
OXYMAT 6 Gas Analyzer for the Determination of Oxygen SIL Safety Manual Supplement to instruction manual ULTRAMAT 6 and OXYMAT 6 OXYMAT 6F 7MB2011, 7MB2017 OXYMAT 6E 7MB2021, 7MB2027 ULTRAMAT/OXYMAT 6E
More informationCHAPTER 29 FAULT / SUCCESS TREE ANALYSIS CONTENTS
Applied R&M Manual for Defence Systems Part C  Techniques CHAPTER 29 FAULT / SUCCESS TREE ANALYSIS CONTENTS Page 1 Introduction 2 2 Definitions 3 3 Features and Analysis 3 4 Construction 4 5 Analysis
More informationFAULT TREE ANALYSIS REPORT FOR THE AUTOMATIC BRAKE SYSTEM. Prepared by
FAULT TREE ANALYSIS REPORT FOR THE AUTOMATIC BRAKE SYSTEM Prepared by Sample Company 111 Foothill Blvd. Suite E156 La Canada Flintridge, California 91011 July 2002 Copyright 2002 by Probabilistic Software,
More informationReliability. 26.1 Reliability Models. Chapter 26 Page 1
Chapter 26 Page 1 Reliability Although the technological achievements of the last 50 years can hardly be disputed, there is one weakness in all mankind's devices. That is the possibility of failure. What
More informationAvoiding AC Capacitor Failures in Large UPS Systems
Avoiding AC Capacitor Failures in Large UPS Systems White Paper #60 Revision 0 Executive Summary Most AC power capacitor failures experienced in large UPS systems are avoidable. Capacitor failures can
More informationPHYSICS EXPERIMENTS (HEAT)
PHYSICS EXPERIMENTS (HEAT) In the matter of physics, the first lessons should contain nothing but what is experimental and interesting to see. A pretty experiment is in itself often more valuable than
More information5 Aleatory Variability and Epistemic Uncertainty
5 Aleatory Variability and Epistemic Uncertainty Aleatory variability and epistemic uncertainty are terms used in seismic hazard analysis that are not commonly used in other fields, but the concepts are
More informationCEM 515: Project Quality Management
King Fahd University of Petroleum & Minerals Department of Construction Engineering & Management CEM 515: Project Quality Management SIX SIGMA FOR PROJECT MANAGERS GROUP# 1 Monday, December 11, 2006 OUTLINE
More informationGeneric Reliability Evaluation Method for Industrial Grids with Variable Frequency Drives
Energy and Power Engineering, 2013, 5, 8388 doi:10.4236/epe.2013.54b016 Published Online July 2013 (http://www.scirp.org/journal/epe) Generic Reliability Evaluation Method for Industrial Grids with Variable
More informationAvailability Assessment of Generating Units of Balimela Hydro Electric Power Station (510 MW) A Markovian Approach
American Journal of Engineering Research (AJER) 24 American Journal of Engineering Research (AJER) eissn : 232847 pissn : 232936 Volume3, Issue2, pp4449 www.ajer.org Research Paper Open Access
More information5.3. The Poisson distribution. Introduction. Prerequisites. Learning Outcomes. Learning Style
The Poisson distribution 5.3 Introduction In this block we introduce a probability model which can be used when the outcome of an experiment is a random variable taking on positive integer values and where
More informationAdvanced Fault Tree Analysis for Improved Quality and Risk Assessment
Advanced Fault Tree Analysis for Improved Quality and Risk Assessment JussiPekka Penttinen 1, Timo Lehtinen 2 Abstract Traditional fault tree analysis (FTA) has formed a common language for the modelling
More informationCEMEP UPS. The high environmental performance solution for power supply to highavailability data centers
CEMEP UPS The high environmental performance solution for power supply to highavailability data centers Exchanges of information and communication needs are growing at an exponential rate. That growth
More informationCHAPTER 15 SOFTWARE R&M ANALYSES CONTENTS
Applied R&M Manual for Defence Systems Part B R&M Related Activities CHAPTER 15 SOFTWARE R&M ANALYSES CONTENTS Page 1 Introduction 2 2 Abbreviations 2 3 Software 3 4 Software Application R&M Techniques
More informationCloud Computing Disaster Recovery (DR)
Cloud Computing Disaster Recovery (DR) Dr. Sanjay P. Ahuja, Ph.D. 201014 FIS Distinguished Professor of Computer Science School of Computing, UNF Need for Disaster Recovery (DR) What happens when you
More informationReliability in Electronics
Technical Article Reliability in Electronics CONTENTS Introduction 1.1 Failure Rate 1.2 Reliability 1.3 Mean Time Between Failures (MTBF) Mean Time to Failure (MTTF) 1.4 Service Life (Mission Life, Life)
More informationBAYES' THEOREM IN DECISION MAKING Reasoning from Effect to Cause
BAYES' THEOREM IN DECISION MAKING Reasoning from Effect to Cause by Jack V. Michaels, PE, CVS Value Engineering Department Martin Marietta Orlando Aerospace ABSTRACT Thomas Bayes (17021761) was an English
More informationContinuous Random Variables and Probability Distributions. Stat 4570/5570 Material from Devore s book (Ed 8) Chapter 4  and Cengage
4 Continuous Random Variables and Probability Distributions Stat 4570/5570 Material from Devore s book (Ed 8) Chapter 4  and Cengage Continuous r.v. A random variable X is continuous if possible values
More informationSOFTWARE ENGINEERING
SOFTWARE ENGINEERING Chapter 26 Quality Management ETAM MEMBERS RN N 3521010116 Murali T 3521010117 Muralitharan S 3521010118 Narasimhan K 3521010119 Navaneethakrishnan D Areas Covered What is software
More informationMASTER S THESIS. Faculty of Science and Technology. Study program/ Specialization: Spring semester, Risikostyring Offshoresikkerhet
Faculty of Science and Technology MASTER S THESIS Study program/ Specialization: Risikostyring Offshoresikkerhet Spring semester, 2012 Open / Restricted access Writer: Monphen Toungsetwut Faculty supervisor:
More informationMaximizing UPS Availability
Maximizing UPS Availability A comparative assessment of UPS designs and deployment configurations for the highavailability data center By Chris Loeffler Product Manager, BladeUPS & Data Center Applications
More informationReliability of Data Storage Systems
Zurich Research Laboratory Ilias Iliadis April 2, 25 Keynote NexComm 25 www.zurich.ibm.com 25 IBM Corporation Longterm Storage of Increasing Amount of Information An increasing amount of information is
More informationFatigue Life Estimates Using Goodman Diagrams
Fatigue Life Estimates Using Goodman Diagrams by Robert Stone The purpose of this paper is to review the proper methods by which spring manufacturers should estimate the fatigue life of a helical compression
More informationNote 5.1 Stress range histories and Rain Flow counting
June 2009/ John Wægter Note 5.1 Stress range histories and Rain Flow counting Introduction...2 Stress range histories...3 General...3 Characterization of irregular fatigue loading...4 Stress range histogram...5
More information